In vehicle air conditioners, an aspirator that produces a reduced-pressure state through a Venturi effect by using fluid is used in order to guide vehicle interior air to a portion where a temperature sensor is installed for detecting a vehicle interior temperature. In general, the aspirator includes a nozzle that aspirates secondary air, that is, vehicle interior air, into the portion where the vehicle interior temperature sensor is installed; a main body that forms an airflow path at the outer circumference of the nozzle so as to surround the nozzle; a primary-air inflow path that communicates with the airflow path of the main body and into which part of an airflow is made to flow from an air conditioning unit; and a diffuser that is connected to an open end of the main body and has a throat portion in the vicinity of which the tip of the nozzle opens.
The following aspirators have been proposed as this kind of aspirator: an aspirator in which the axis of the nozzle, which aspirates secondary air, is aligned with a maximum-wind-speed portion of the wind speed distribution of the primary air in the throat portion of the diffuser, in order to increase the amount of aspirated secondary air (see Japanese Unexamined Patent Application, Publication No. Hei-5-155227); and an aspirator in which the center line of the primary-air inflow path is provided eccentrically with respect to the central axis of the main body, and the primary air is turned into a swirling flow in the main body, thereby increasing the wind speed in the throat portion of the diffuser and increasing the amount of aspirated secondary air (see Japanese Unexamined Patent Application, Publication No. 2005-280433).